Underground spaces are used for a variety of purposes. For example, an underground tunnel may be used for military purposes, for transportation, for utility/water supplies, and/or for smuggling contraband such as weapons, drugs, or even people. Many tunnels are located along the southwest border of the United States and are used for drug trafficking.
It is often desirable to know when an underground space was created. For example, when law enforcement discovers a drug trafficking tunnel and shuts it down, it is useful to know who owned and occupied the land when the tunnel was constructed. Accordingly, there is a need for improved systems, methods, and techniques for determining the age of a tunnel.